<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
</head>
<body>

</body>
<script>
	// // 隔离变量，不同作用域下同名变量不会有冲突
	// let userName = "zhangsan";
	// function fn(){
	// 	let userName = "lisi";
	// 	console.log(userName);// lisi
	// }
	// fn();
	// console.log(userName);// zhangsan
</script>
</html>